A video projector receives a video signal and projects the corresponding image on a projection screen or any other surface. Video projectors use a bright light to project the image, and most modern ones can correct any curves, blurriness, and other inconsistencies through manual or automatic settings. Video projectors are widely used for conference room presentations, classroom training, home theater, and many more applications.
Recent technological developments have made it possible to place all of the necessary projector components within the small package of a handheld device, such as cellular telephones, PDAs, laptops, portable music players, gaming devices, and the like. A specific projection technology that is particularly well suited for use in small portable devices is Laser Projection Display (LPD). LPD is a projection display technology that uses three different colored lasers coupled with scanning mirrors to produce full color, high resolution images. Their small size and low power usage make LPD projectors a great choice for use in these small packages.
One problem with hand-held projectors is image stability. If a user's hands tremble or move, the image that he is projecting will naturally reflect this movement of the user's hands. This problem is amplified as the distance between the user and the projection surface increases.
An attempt has been made to automatically compensate for movement of a projector. This approach detects movement of the projector by constantly monitoring a static object or through movement detection means, such as a gyroscope, a ball of liquid, and/or acceleration sensors. Once movement is detected, the movement is compensated for by moving a mirror that reflects the entire rendered frame to the viewing surface. This process allows repositioning of an entire image.
LPD scanning projectors reflect each pixel, one at a time, systematically, in rows and column. To accomplish this precise reflection, LPD scanning projectors utilize two mirrors that move at different speeds. To stabilize an LPD image using the prior-art method for projectors, an additional driven mirror that would reflect the entire image would have to be added and controlled. This would add cost, size, and an increase in potential failures. Prior-art image compensation methods have not addressed adjusting multiple mirrors with varying speeds.
Therefore, a need exists to overcome the problems with the prior art as discussed above.